Finally got to perform a full convergence on the set two days ago, and the newly manufactured vertical convergence transformer is doing a fine job. The procedure improved convergence to the point where the overall 15GP22 image -- to use the vernacular of the streets -- looks sharp as a gnat's ass.
A minor inconvenience is the weather. Yesterday is the second time in recent history that a spell of humid weather affected the high voltage. Not certain where the damn humidity planted the unwanted load, but it's highly unlikely that the new transformer is a factor. The last time this happened was a week after replacing the transformer. A three-week hiatus with no power applied to the set brought it back: the high voltage recovered after the weather turned dry.